In Ext JS 4, we have the MVC pattern to build and clean well-structured applications. Looking back at our past few practical chapters, though, it seems difficult to imagine going back to MVC from the MVVM architecture that Ext JS gives us because, in each example, we've used view models to great effect to provide a logical way for data to flow through our application.

The interesting thing about these examples is how little code we write in many situations. Analyzing the application requirements and spiking a few tricky areas leads to writing a small amount of configuration of UI, controllers, view models, and so on. Ext JS automatically builds the plumbing through which our data can flow.

It's another example of why application architecture is so important, particularly when combined with a strong understanding of the tools at hand. It would be very easy for a naïve developer to jump in and start writing code to manually handle movement of data from an API through to...